1. Field of the Invention
The present invention relates to a direct-drive washing machine having a drive motor which drives an inner tub or pulsator directly, and more particularly, to a direct-drive washing machine enabling to drive the inner tub or pulsator selectively in accordance with a demanded condition.
2. Background of the Related Art
Generally, washing machines are divided into clutch-drive system washing machines, direct-drive system washing machines, and the like in accordance with a power transfer system. The clutch-drive system transfers a power generated from a drive motor to a pulsator using a belt, pulley, and clutch. And, the direct-drive system drives a washing vessel by connecting a drive motor directly to the washing vessel.
FIG. 1 illustrates a cross-sectional view of a direct-drive washing machine according to a related art.
Referring to FIG. 1, a direct-drive washing machine according to a related art includes a case 202 of which upper portion is open, an outer tub 206 supported by a support rod 204 inside the case 202 so as to be filled with a washing water, an inner tub 208 installed inside the outer tub 206 to revolve so as to carry out a cleaning process of a laundry, and a drive motor 212 installed under the outer tub 206 so as to drive to revolve the inner tub 208 through a tub shaft 210.
A pulsator 214 is formed in one body inside the inner tub 208 so as to generate a washing current.
The direct-drive washing machine according to the related art comes into cleaning the laundry as the drive motor 212 is driven to revolve the inner tub 208 having the pulsator 214 formed in one body to generate a frictional power with the laundry.
Yet, in the direct-drive washing machine according to the related art, the inner tub 208 revolves regardless of a species and quantity of the laundry and a washing water quantity so as to carry out the washing process, whereby the laundry of small quantity comes into revolution in the same direction of the inner tub. In this case, the frictional power is hardly generated so as to reduce a washing power of the laundry.
Moreover, the above-constituted direct-drive washing machine according to the related art is constituted so as to carry out the washing process by revolving the inner tub 208. Compared to the system of carrying out the washing process by revolving the pulsator 214 only, such a direct-drive washing machine according to the related art has an increasing inertia to increase a load of the drive motor 212 so as to degrade a drive efficiency.
Furthermore, in order to operate freely the drive motor 21 for speed, torque, slope, and the like, the above-explained direct-drive washing machine according to the related art uses a BLDC(brushless DC) motor requiring an additional controller to be controlled, whereby a cost is increased.